Identifying a glass frosting chemical

Question

I have purchased an "unknown" white coloured powder from the market which can frost glass objects. Here are some properties of this powder

1. White in colour
2. When mixed with HCL or water, it results in the soluion becoming ice cold, the reaction is endothermic.
3. When kept for a while (10 minutes) the white powder settles at the bottom of the plastic vessel and the acid floats above it.
4. When stirred, the entire solution becomes milky
5. When glass is dipped in this solution for 90 seconds, it becomes frosted/translucent.

Since I am not sure what this chemical is, I cannot determine the safest method to dispose it. The person from whom I brought this told me to put it down the drain, but I wouldnt choose to do that before I know if it will not effect the water table near my locality.

Can someone point out what could this powder be, and the best way to dispose it off?

Answer 1

The most common glass-etching powders are solid ammonium bifluoride and solid potassium bifluoride. See for example the Material Safety Data Sheet for “EtchON Acid-Frost Glass Frosting Powder”, or this one. This is not a definite identification, but it fits your description, and those two are the most commonly available such chemicals.

Disposal is a bit tricky. Definitely don't put it down the drain! The first MSDS linked above says:

Ecological Information:
Noxious for the water inhabitants. Avoid disposal into rivers, sewer system and land penetration.

The second gives a hint at disposing of it:

Disposal Instructions:
All wastes must be handled in accordance with local, state and federal regulations. Material can be converted to a less hazardous material by weak reducing agents followed by neutralization.

So, contact your local waste management authorities, and ask them how to proceed. Do not attempt it neutralize it by yourself unless (i) you know what you are doing, and (ii) you have the appropriate hardware (fume hood, e.g.).